The purpose of the investigation was to study skeletal muscle bioenergetics in Black vs. White males. 3/P-NMR spectroscopy was used to continuously monitor in vivo changes in intramuscular inorganic phosphate (Pi), phosphoctreatine (PCr), and pH during exercise. The changes were used to compare mitochondrial function between healthy Black and White males. Percent body fat, peak oxygen consumption (VO2peak), the maximum voluntary contraction (MVC), and skeletal muscle bioenergetics were studied in nine healthy Black males and nine healthy White males (age 18-24 yrs.). NMR measurements were performed on a 2.35-Tesla 31-cm magnet with a home-built NMR spectrometer console. 31P-NMR spectra were obtained from the flexor carpi radialis muscle at rest and during a carefully controlled wrist flexor exercise protocol, performed inside the magnet on a homebuilt ergometer. The power output was calculated from the aspect of the ergometer system. Relative concentrations of Pi, PCr, and intramuscular pH were determined from the 31P NMR spectra. Peak oxygen consumption was lower in Blacks compared to Whites. No significant differences were observed in the Pi/(PCr+Pi) ratio between the two groups. The resting pH was lower in the Black group compared with the White group, and exercise caused a statistically significant difference in the change in pH in Blacks compared to the Whites. These preliminary results indicate a possible difference in the mitochondrial function in Blacks compared to Whites. Further experiments are planned for the coming year to confirm these findings.